Does useBeforeUnload have a condition to remove the listener?

[alexandre-boily]

From the mdn web doc usage, it seems like constantly having a listener on beforeunload impacts performance.

In Firefox, beforeunload is not compatible with the back/forward cache (bfcache): that is, Firefox will not place pages in the bfcache if they have beforeunload listeners, and this is bad for performance.

It is therefore recommended that developers listen for beforeunload only when users have unsaved changes so that the dialog mentioned above can be used to warn them about impending data loss, and remove the listener again when it is not needed. Listening for beforeunload sparingly can minimize the effect on performance.

From my understanding of the code, we don't really have a condition to remove the listener if it can not be used. Is this an oversight, or did I misunderstand it?

Example on how react-beforeunload handles it : https://github.com/jacobbuck/react-beforeunload/blob/a271f7a01f9fd5309d9f859f5e805c9c3c8ba28c/src/useBeforeunload.js#L10